When Lightning Strikes, Spark Branches Reconnect

Sep 24, 2008

Bolts of lightning often resemble the forked, branches of trees. Similar to tree branches, lightning sparks typically spread apart. Recently, physicists at Centrum voor Wiskunde un Informatica and Eindhoven University of Technology in the Netherlands have for the first time determined the conditions that allow for spark branches to reconnect, by overcoming the electrostatic repulsion that usually causes them to separate.

These branches, known as streamers, are the building blocks of sparks and lightning. They are actually made of air that has been converted into long, thin, twisty rods of plasma. These streams of plasma serve as a medium or path for electricity to travel through.

The physicists recreated their own lightning environment using sophisticated computer simulations. They studied the dynamics of 3-dimensional streamers in nitrogen-oxygen mixtures like air. They found that with varying air composition and pressure, streamers can either repel or attract each other unexpectedly.

Under the right conditions, the streamers can either branch out or recombine, like two rivers coming to together. They concluded that branches reconnect because of a process called photo-ionization, where a cloud of electrons is created between two streamers that eventually makes the coalesce into a single, wider one.

Their study offers new a perspective into understanding lightning's variable behavior.

Citation: A. Luque, U. Ebert, and W. Hundsdorfer, Physical Review Letters (15 August 2008), link.aps.org/abstract/PRL/v101/e075005

Source: APL

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Alizee
Sep 24, 2008
This comment has been removed by a moderator.
mgmirkin
2.3 / 5 (3) Sep 26, 2008
So NOT anything new... It's been known for a long time that parallel electric currents have a long-range attractive and short-range repulsive force... Larger "streamers" are simply twisted pairs (or more) of smaller streamers (filaments).

Egaah! Why do they have to keep "rediscovering" known facts?

http://www.plasma...entation

As can also be seen in the Dense Plasma Focus, which has a number of braided filaments spaced around the outside of the over all discharge.

http://www.plasma...ma_focus

Other filaments operate in much the same way, smaller filaments attract into larger twisted pairs (themselves filaments) and those can twist into larger braided pairs.

This isn't NEW!